The present invention relates to a novel water-treating agent and a method for treating water with the novel water-treating agent. More precisely, the present invention relates to a novel water-treating agent which prevents scale, sludge, and slime deposition.
The novel water-treating agent of the present invention can be used in, for example, heating pipes, heat exchangers, condensers, reaction vessels, chemical reactors, and various pipe runs found in, for example, boilers, cooling water systems, hot water systems, chemical plants, and dust collecting water plants.
The novel water-treating agent of the present invention prevents such problems as heat transfer failure, flow rate reduction, and corrosion that are caused by the adhesion or deposition of scale, sludge, and slime onto heating pipes, heat exchangers, condensers, reactors for polymerization, and various other pipe lines.
The present invention also relates to a method of using the water-treating agent for treating water in, for example, heating pipes, heat exchangers, condensers, reaction vessels, chemical reactors, and various pipe runs found in, for example, boilers, cooling water systems, hot water systems, chemical plants, and dust collecting water plants.
Heretofore, polyphosphates and carboxylic acid polymers have been used as scale inhibiting and fouling prevention agents in boilers, cooling water systems, dust collecting water plants and water supply piping systems to prevent the adhesion of scale onto the surfaces of the metal parts kept in contact with water, to prevent the deposition of sludge onto such metal parts, and to prevent the local corrosion in the area under the fouled parts covered with scale and slime.
However, polyphosphates are inadequate in that they are easily hydrolyzed to give orthophosphates, which in turn precipitate as calcium phosphate in water systems having high pH and high calcium hardness at high temperatures. Hence, polyphosphates too often accelerate scale troubles instead of alleviating them.
In addition, waste waters containing phosphorus are problematic because the phosphorus laden waters cause eutrophication in closed water areas such as lakes, marshes and island seas. Hence, the use of phosphorus containing chemicals must be limited and are often regulated by law.
On the other hand, carboxylic acid polymers have their own problems. They form insoluble salts in water containing high concentrations of polyvalent metal ions, with the result that the polymers are not effective in such water. In particular, where the polymers are applied to water with a high calcium ion concentration, the water becomes cloudy due to the calcium salts forming and precipitating.
In Japanese Laid Open Patent Application No. 2-9496, a phosphorus free water-treating agent for scale inhibition is proposed which comprises a copolymer of a conjugated diene-sulfonic acid and (meth)acrylic acid which is said to be effective, even in systems having high metal ion concentrations, without being precipitated therein.
However, when compared with sodium polyacrylate, which has heretofore been used in conventional water-treating agents, the copolymer of 2-9496 is superior to sodium polyacrylate but is still not completely satisfactory. Therefore, a water-treating agent having much improved effectiveness against scale retarding and fouling is still needed.